<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      function fn(a){
        if((a %4===0 && a%100 !==0 ) || a%400===0){
            document.write(`${a}是闰年`)
        }else{
            document.write(`${a}不是闰年`)
        }
      }
    fn(parseInt(prompt("请输入年份")))
    </script>
  </body>
</html>
